The section has continued to investigate two major non-pharmacological treatments of substance abuse, contingency management and cognitive/behavioral therapy. Abstinence reinforcement contingencies, rooted in the Experimental and Applied Analysis of Behavior, are based on the empirically-derived assumption that drug abuse is operant behavior maintained and modifiable by its consequences and thus sensitive to the types of environmental variables which have been shown in laboratory and applied research to affect a wide range of operant behaviors. Our first study validated the application of the principle of reinforcement, the central principle in operant conditioning, to the treatment of cocaine use disorder. Our second major study was completed in the past year. Participants were inner-city, intravenous, polydrug abusers receiving standard methadone maintenance treatment. Experimental patients were exposed to reinforcement contingencies in which they received vouchers for cocaine-free urines. The vouchers had monetary values and were exchangeable for goods and services designed to support drug-free lifestyles. A unique and important aspect of the procedure is that the monetary value of the vouchers increased as the number of consecutive cocaine-free urines increased; cocaine-positive urines reset the value of the next voucher back to the initial low value. Control patients received noncontingent vouchers that were matched in pattern and amount to the vouchers received by abstinence reinforcement patients. Patients exposed to the abstinence reinforcement contingencies achieved significantly longer periods of sustained cocaine abstinence than controls. To date our studies have shown that voucher-based reinforcement contingencies can produce sustained cocaine abstinence, even in inner-city, intravenous, polydrug abusers who historically have been very difficult to treat by other means, and that the schedule of reinforcement is an important factor in determining treatment outcome. Two follow-up studies in methadone maintenance patients are in progress. The contingency management procedure is also being applied in a study to improve compliance with naltrexone treatment